How to minimize/soften the shadows?
You don't need much. A single large light source (the less sources the easier it is to deal with multiple shadows), and a semi-refletive surface for the ground.

Larger sources will create less defined shadows.

Why?

Do a search online the concepts of Umbra and Penumbra.

Larger sources will make the umbra be smaller than the penumbra.



(imgage source: http://www.viz.tamu.edu/faculty/parke/ends375f04/notes/sec7_5.html)

So in this case just make a large area light and let it do the magic.



For a nicer tonal reproduction use the Filmic Blender OCIO Confuguration, you can read more about it here:Render with a wider dynamic range in cycles to produce photorealistic looking images